1. Technical Field
The present invention relates generally to the field of streaming. More specifically, the present invention is related to monitoring for streaming data loss in packetized form using the Internet Protocol (IP).
2. Background
Many electronic networks such as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs) are increasingly being used to transport streaming media whose real-time data transport requirements exhibit high sensitivity to data loss. While layer 4 protocols such as RTP and TCP incorporate sequence numbers for the detection of packet loss, many applications do not use these protocols due to the additional protocol overhead and resultant increased network utilization required or for other reasons. Nevertheless, unreliable layer 3 networks such as those using IP may lose packets under a variety of conditions such as transient oversubscription, electrical noise ingress, etc. The technical literature is replete with various schemes to implement Quality of Service (QOS) on such networks to address the requirements of streaming media, especially when intermixed with conventional, time and loss insensitive, best-effort delivery protocol stack data traffic. To verify the QOS intended effectiveness, systems must be tested. Tests and monitoring are used to verify the QOS design, implementation, and system configuration after deployment. Regardless of whether QOS-enabled or non-QOS-enabled networks are employed, it is necessary to verify the behavior of packet loss in the network while operating under test and during normal operating conditions. Verifying packet loss behavior requires a protocol field that changes (typically incrementing) with each successive packet such that a receiving device can determine if packets are received out of sequence, whether packets are missing, and the ability to numerically characterize the loss in terms of total loss, burst loss size, and loss frequency. The IP layer 3 protocol contains no such fields leaving this function for implementation in layer 4 protocols
Alternatively, still higher layer protocols such as layer 7, the Application Layer, may include such a sequence field. An example for the streaming media application is the MPEG Transport Stream which, in addition to carrying encoder clock information and program specific information, also includes a Continuity Counter which can be used to detect packet loss. However, like the choice for including a layer 4 protocol, this requires additional encoder complexity and protocol overhead which may not be able to be tolerated in certain types of deployments.
Whatever the precise merits, features, and advantages of the above-mentioned prior art schemes, they fail to achieve or fulfill the purposes and/or the economies of the present invention.